Magnetically driven pump for absorption refrigeration system

ABSTRACT

An absorption refrigeration system having a generator, a condenser, an evaporator, an absorber, and a fluid transfer apparatus for pumping liquids in the system. The fluid transfer apparatus includes a plurality of spaced housings sealingly secured to the exterior surface of a cylindrical nonferromagnetic wall. One or more scoop pump pans are rotatably mounted within each of the housings for rotation about the nonferromagnetic wall. An annular magnetic coupling member is secured to the rotor member within each housing. A second annular magnetic coupling member is mounted exteriorly of each housing in coupling relation with the annular magnet therein and is attached to an external electric motor to drive the scoop pump pans within the housings.

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Leonard, Jr. 1 1 May 22, 1973 54 MAGNETICALLY DRIVEN PUMP FOR 2,124,914 7/1938 Fottinger ..415 s9 ORPTI N R RI ERA 3,465,681 9/1969 Zimmermann ..417 42o SYSTEM Primary ExaminerWil1iam L. Freeh [75] Inventor: Louis B. Leonard, Jr., Dew1tt, N.Y. Assistant Examiner john winbum [73] Assignee: Carrier Corporation, Syracuse,N.Y. Attorney-Harry Martin, and Raymond Curt' 22 Filed: Apr. 12, 1971 m [21] App1.No.: 133,053 [57] ABSTRACT Related U,S A li ation D t An absorption refrigeration system having a generator,

a condenser, an evaporator, an absorber, and a fluid Division Of S81. NO. March 18, Pat. transfer apparatus for in the System- The fluid transfer apparatus includes a plurality of spaced housings sealingly secured to the exterior surface of a cylindrical nonferromagnetic wall. One or [58] Fie'ld 4l7/420 415/88 more scoop pump pans are rotatably mounted w1th1n "415/89310/104 each of the housmgs for rotatlon about the nonferromagnetic wall. An annular magnetic coupling [56] References Cmd member is secured to the rotor member within each housing. A second annular magnetic coupling member UNITED STATES PATENTS is mounted exteriorly of each housing in coupling relation with the annular magnet therein and is attached R26,094 10/1966 Zimmermann ..417/42O to an external electric motor to drive the Scoop pump 211,347 1/1879 de Rom1l1y ..415/89 ans within the housin S 1,441,589 1/1923 Krogh ..415/89 p g 2 Claims, 1 Drawing Figure MAGNETICALLY DRIVEN PUMP FOR ABSORPTION REFRIGERATION SYSTEM CROSS-REFERENCE TO RELATED APPLICATION This application is a division of application Ser. No. 20,770, filed Mar. 18, 1970, now US Pat. No. 3,608,330 entitled ABSORPTION REFRIGERA- TION SYSTEM.

BACKGROUND OF THE INVENTION This invention relates to absorption refrigeration systems and fluid transfer apparatus therefor. It is known to employ centrifugal pumps to circulate absorbent solution and refrigerant in the system. Centrifugal pumps require that a positive head exist in order to force the liquid into the impeller eye without flashing and vapor binding, and this requirement adds undesirable height to the absorption machine and limits the application of centrifugal pumps thereto.

Accordingly, it has been proposed to circulate absorbent solution and refrigerant in an absorption refrigeration system by using one or more scoop pumps generally taking the form of a closed chamber within which is rotatably mounted a rotor or peripherally flanged disc for centrifugally irnpelling at a high tangential velocity liquid directed into the chamber through an inlet conduit, the liquid which is thus flung outwardly being picked up by a scoop or eduction tube. Scoop pumps have among their advantages simplicity of construction, and normally will not cavitate even in the absence of suction heads.

However, the prior drive arrangements for scoop pumps have presented certain problems. It is known to drive the scoop pumps by an exteriorly mounted motor having a shaft connected through a seal in the scoop pump housing but such seals are subject to leakage in use. It has also been proposed to drive a scoop pump by means of axially confronting magnetic couplings connected to an exteriorly located motor. These magnetic couplings require close tolerances in order to provide an efficient coupling and to avoid possible misalignment problems. However, in prior magnetic coupling arrangements, bearing or other wear, such as occasioned by axial thrusts impaired during operation, can result in interference and destruction of the coupling parts. Still other arrangements proposed have made replacement of motors impossible without removing the pump from the system or opening it to the atmosphere.

SUMMARY OF THE INVENTION In accordance with this invention, there is provided an absorption refrigeration machine, which embodies therein fluid transfer apparatus comprising a housing having a central, generally cylindrical, nonferromagnetic wall. An annular pump rotor member, including an annular permanent magnet, is supported within the housing in surrounding relation with the cylindrical wall. A scoop pump, for circulating absorbent solut on and refrigerant through the absorption refrigeration system, is secured to the annular pump rotor member within the housing. An annular drive member, including an annular permanent magnet, is positioned in the cylindrical wall exterior to the housing in magnetically coupled relation with the magnet in the housing. The rotor member is coupled to a motor for driving the rotor within the housing to operate the pump. The arrangement readily lends itself to any desired number of pumps being driven by a single motor which can be replaced without disturbing the pump or opening the machine to atmospheric pressure.

BRIEF DESCRIPTION OF THE DRAWING The single view is a schematic flow diagram, partially in cross section, of an absorption refrigeration system embodying a fluid transfer apparatus in accordance with this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT In a preferred embodiment of this invention, there is provided an absorption refrigeration system which utilizes water as a refrigerant and an aqueous solution of lithium bromide as an absorbent. Strong solution as referred to herein is a concentrated solution of lithium bromide, which is strong in absorbing power. Weak solution is a dilute solution of lithium bromide which is weak in absorbing power.

Referring now to the drawing, there is shown an ab sorption refrigeration system comprised of a generator 10, a refrigerant condenser 12, an absorber 14, an evaporator 16, a solution heat exchanger 18, and fluid transfer apparatus 15. A purge unit 20 may be employed to remove relatively noncondensable vapors from the system.

Generator 10 comprises a boiler to which weak absorbent solution is directed from heat exchanger 18 through conduit means 22, the solution being caused to boil in the generator by a heat source such as steam pipe 24 to concentrate the absorbent solution by vaporizing refrigerant, which passes into condenser 12 through passage 26.

Refrigerant condensed in condenser 12 is directed by conduit means 28 to evaporator 16. A heat exchanger 30 through which a heat transfer medium to be cooled flows, is located in the evaporator. A spray header 32 is also disposed in the evaporator to wet the surfaces of the heat exchanger 30 with liquid refrigerant recirculated from the evaporator. Refrigerant in evaporator 16 is evaporated to cool liquid passing through heat exchanger 30 and the water vapor passes through passage 34 to absorber 14.

Absorbent solution in absorber l4 absorbs water vapor from evaporator 16. Heat exchangers 36 and 38 are connected to a source of cooling medium, such as water, to remove waste heat from the refrigeration cycle. Also located in the absorber 14 is spray header 40 which serves to wet the surfaces of heat exchanger 36 with strong absorbent solution.

Fluid transfer apparatus 15 comprises a cylindrical transverse nonferromagnetic wall member 62. Housings and 61 are welded or otherwise secured in sealing relation with the exterior surface of wall member 62 and each defines an annular sealed cavity containing a pump mechanism. A pair of spaced annular permanent magnets 65 and 66 are secured to shaft 67 which rotates in bearing support members 68 and 69 exteriorly of housings 60 and 61, within the confines of cylindrical wall member 62. An electric motor 70 is attached by coupling 71 for driving shaft 67.

A rotor base member 75 is mounted on bearings 76 and 77 for rotation within housing 60 about the exterior surface of wall member 62. An annular permanent magnet 78 is secured to rotor base 75 and is laterally positioned adjacent and in magnetic coupling relation with exterior magnet 65. A radially extending pan member 79 is connected with axially extending, radially spaced pan members 80 and 81 to form a pair of channel-shaped annular scoop pump pans. Pan mem ber 80 forms a pan or chamber 98 for pumping strong solution, and pan member 81 forms a chamber or pan 96 for pumping weak solution. A stationary inlet passage 110 is disposed within the housing for passing strong solution to chamber 98, and a stationary eduction conduit 116 is disposed within pan 98 for receiving solution impelled into its open inlet orifice 116a facing opposite the direction of rotation of the pan. Similarly, a stationary discharge conduit 106 is disposed within the housing for discharging weak solution into pan 96 and an eduction conduit 114 extends into pan 96 and faces so as to receive solution impelled into its open inlet end or orifice 114a. A suitable stationary pickup scoop 108 may be employed to transfer any liquid which splashes or drains into the bottom of housing 61 into chamber 96 during operation of the system.

in a like manner, rotor base 85 is supported on the exterior surface of wall 62 by bearings 86 and 87 within housing 61. Annular permanent magnet 88 is positioned in coupling relation with magnet 66 and secured to base 85. Pan members 89 and 90 form a rotatable channel-shaped scoop pump pan or chamber 94 having an inlet conduit 102 and an eduction conduit 104 disposed for receiving liquid impelled into its open eduction orifice 104a. A clean-up scoop 91 removes any liquid from the bottom of housing 61. It will be noted that any number of pump sections may be provided in axially spaced relation about wall 62 and that the sections may be sealed from each other or may be open to one another as desired by suitable design modification.

During operation, rotation of motor 70 causes magnets 65 and 66 and their coupled magnets 78 and 88 to rotate. Weak solution from absorber 14 passes through line 106 into pan 96. The weak solution is rotated with the pan, impelled into the open eduction orifice 114a and pumped through eduction conduit 114, heat exchanger 18 and passage 22 to generator for reconcentration. Concentrated strong solution drains from generator 10 through passage 110 into scoop pump pan 98 from which it is pumped through passage 116 through spray header 40 over absorber heat exchanger 36 for the absorption of refrigerant vapor therein. Refrigerant condensate drains through a suitable float valve or other restriction from condenser 12 into evaporator 16 and passes through passage 102 into scoop pump 94 where it is picked up by eduction orifice 104a and passed through spray header 32 over evaporator heat exchanger 30 for evaporation in heat exchange relation with a medium to be cooled, thereby producing the refrigeration effect.

The fluid transfer apparatus in accordance with this invention overcomes a number of shortcomings of previously utilized pumps. For example, the desired diameter of a properly designed scoop pump may not always correspond with the desired electric motor rotor diameter and a pump in accordance with this invention may be provided with any desired diameter or, in the alternative, wall member 62 may be made in sections of different diameters to accommodate different pump head requirements. Furthermore, electric motor 70 being entirely exterior of the pump housing is readily replaceable in the event of bum-out or other failure as are the driving magnets 65 and 66 without exposing the system to the deleterious effects of air. The arrangement also lends itself to the utilization of any conventional motor of either the electric or fluid operated type. An unlim- 5 ited number of pumps, either sealed from each other or not, as desired, may be utilized in accordance with this invention; and each of the pumps, although varying in head, capacity requirement and function, may be driven from a single electric motor. The system also avoids excessive thrust loads on the bearings and attendant failures as well as avoiding critical assembly tolerances associated with axial drives.

While a preferred embodiment of this invention has been described for purposes of illustration, it will be appreciated that the invention may be otherwise embodied within the scope of the following claims.

I claim:

1. A fluid transfer apparatus adapted for pumping a liquid, said fluid transfer apparatus comprising:

A. housing member, said housing member having a transverse, axially extending, cylindrical, non-ferromagnetic wall extending through the housing member;

B. a rotor member disposed in said housing member in coaxial relation with the cylindrical wall portion of said housing member; said rotor member having 1. a pair of axially spaced annular bearings disposed in the housing member in coaxial relation with the cylindrical wall portion of said housing member for rotatably journaling the rotor member in the housing member;

2. a scoop pump pan member carried by said rotor member and disposed in said housing member in coaxial relation with the cylindrical wall portion of the housing member, said scoop pump pan member being axially disposed in the housing member between said spaced annular bearings;

3. a driven magnet disposed in said housing member and carried by said rotor member, said driven magnet having a cylindrical surface in coaxial relation with and close proximity to the cylindrical wall portion of said housing member;

C. an inlet conduit disposed for discharging liquid into said scoop pump pan member, and a stationary eduction conduit disposed in said pan member for intercepting a rotating body of liquid in said pan member during operation of said apparatus and for passing liquid from the housing member;

D. driving magnet having a cylindrical surface disposed outside said housing member in coaxial relation with and close proximity to the cylindrical wall portion of the housing member, said driving magnet being axially disposed along the axis of the cylindrical wall portion of the housing member in alignment with the driven magnet whereby said driving and driven magnets are in magnetically coupled relation with each other;

E. motor means exterior of the housing member connected for rotating the driving magnet, thereby rotating the scoop pump pan member within the housing member to pump liquid in the system.

2. A fluid transfer apparatus as defined in claim 1 wherein said driven annular magnet member and said 5 driving annular magnet member are also axially disposed between said spaced'annular bearings. 

1. A fluid transfer apparatus adapted for pumping a liquid, said fluid transfer apparatus comprising: A. housing member, said housing member having a transverse, axially extending, cylindrical, non-ferromagnetic wall extending through the housing member; B. a rotor member disposed in said housing member in coaxial relation with the cylindrical wall portion of said housing member; said rotor member having
 1. a pair of axially spaced annular bearings disposed in the housing member in coaxial relation with the cylindrical wall portion of said housing member for rotatably journaling the rotor member in the housing member;
 2. a scoop pump pan member carried by said rotor member and disposed in said housing member in coaxial relation with the cylindrical wall portion of the housing member, said scoop pump pan member being axially disposed in the housing member between said spaced annular bearings;
 3. a driven magnet disposed in said housing member and carried by said rotor member, said driven magnet having a cylindrical surface in coaxial relation with and close proximity to the cylindrical wall portion of said housing member; C. an inlet conduit disposed for discharging liquid into said scoop pump pan member, and a stationary eduction conduit disposed in said pan member for intercepting a rotating body of liquid in said pan member during operation of said apparatus and for passing liquid from the housing member; D. driving magnet having a cylindrical surface disposed outside said housing member in coaxial relation with and close proximity to the cylindrical wall portion of the housing member, said driving magnet being axially disposed along the axis of the cylindrical wall portion of the housing member in alignment with the driven magnet whereby said driving and driven magnets are in magnetically coupled relation with each other; E. motor means exterior of the housing member connected for rotating the driving magnet, thereby rotating the scoop pump pan member within the housing member to pump liquid in the system.
 2. a scoop pump pan member carried by said rotor member and disposed in said housing member in coaxial relation with the cylindrical wall portion of the housing member, said scoop pump pan member being axially disposed in the housing member between said spaced annular bearings;
 2. A fluid transfer apparatus as defined in claim 1 wherein said driven annular magnet member and said driving annular magnet member are also axially disposed between said spaced annular bearings.
 3. a driven magnet disposed in said housing member and carried by said rotor member, said driven magnet having a cylindrical surface in coaxial relation with and close proximity to the cylindrical wall portion of said housing member; C. an inlet conduit disposed for discharging liquid into said scoop pump pan member, and a stationary eduction conduit disposed in said pan member for intercepting a rotating body of liquid in said pan member during operation of said apparatus and for passing liquid from the housing member; D. driving magnet having a cylindrical surface disposed outside said housing member in coaxial relation with and close proximity to the cylindrical wall portion of the housing member, said driving magnet being axially disposed along the axis of the cylindrical wall portion of the housing member in alignment with the driven magnet whereby said driving and driven magnets are in magnetically coupled relation with each other; E. motor means exterior of the housing member connected for rotating the driving magnet, thereby rotating the scoop pump pan member within the housing member to pump liquid in the system. 